<!DOCTYPE html>
<html>
  <head>
    <style>

/* None of these selectors should match from content */
input[type=number]::-moz-number-wrapper,
input[type=number]::-moz-number-text,
input[type=number]::-moz-number-spin-box,
input[type=number]::-moz-number-spin-up,
input[type=number]::-moz-number-spin-down {
  background-color: red;
}

    </style>
  </head>
  <body>
    <input type="number" style="-moz-appearance:none;">
  </body>
</html>
